3.1. Climate change
During 2000 and 2020, the average precipitation and temperature in Liaoning Province showed an overall rising trend (Fig. 3). From 2000 to 2010, the average precipitation increased by 13.06%, with an increased rate of 6.97 mm/a. From 2010 to 2020, it decreased by 4.60%, with a decrease rate of 2.78 mm/a. From 2000 to 2010, the precipitation-intensive area shifted from the southwest to the east. From 2010 to 2020, it extended from the east to the north. From 2000-2020, the western part in Liaoning Province was a precipitation-deficient area. The maximum and minimum temperature in Liaoning province increased by 0.02°C and 0.31°C, respectively, from 2000 to 2010, whereas it increased by 0.97°C and 0.78°C, respectively, from 2010 to 2020. All province appeared a spacial distribution of low temperature in the north and high temperature in the south.
3.2. Land use change
During the two phases of 2000-2010 and 2010-2020, cropland was the primary land use type in Liaoning Province, with an average percentage of 47.50%, mainly in the central and northern parts, followed by forest land at 29.23%, mainly in the eastern and western (Table 3, Fig. 4). The area of unused land grew the fastest, with an increasing rate of 56.60%. In contrast, the area of cropland decreased the fastest, with a decreasing rate of 3.89% (Table 3). The area of both grassland and water body showed a trend of improving and then declining. The land use transfer matrix showed that within the two phases, cropland was the largest type of land type transferred out, accounting for 45.87% of the overall transferred area, followed by forest land at 24.09% (Fig. 5). The main transfer directions of cropland were 42.31% for forest land and 31.81% for construction land, and the main transfer directions of forest land were 54.44% for cropland and 19.20% for construction land (Fig. 5). The overall transfer area in 2010-2020 increased by 7.13% compared to 2000-2010.
3.3. Change in ESs
3.3.1. NPP change
During 2000 and 2020, NPP showed a rising trend in Liaoning Province. In 2000, 2010 and 2020, the average NPP were 484.76 gC/m², 539.15 gC/m² and 609.38 gC/m², respectively (Fig. 6). During the two phases of 2000-2010 and 2010-2020, the average NPP increased by 11.22% and 13.03%, respectively, with an increasing rate of 5.44gC/m²/a and 7.02gC/m²/a, and the maximum value also increased by 13.22% and 11.89%, respectively. From 2000 to 2010, the increased areas of NPP accounted for 78.03% in the total study area, major distributed in the middle, southern and southwestern regions, whereas the increase areas of NPP value about 51.37% of the all study area from 2010 to 2020, major distributed in the northern regions and westeren regions.
3.3.2. WY change
WY also appeared an uptrend in Liaoning Province during 2000 and 2020. The mean WY increased from 486.45mm to 547.66mm in 2000-2010, with an increasing rate of 6.12mm/a. From 2010-2020, the mean WY decreased from 547.66mm to 516.79mm during 2010 to 2020, with a decreasing rate of 3.09mm/a. WY showed a similar spatial distribution to the precipitation. From 2000 to 2010, the increase region of WY value about 51.22% of the all study region, major distributed in the northern, southern and eastern, whereas the increase area of WY value accounted for 21.35% of the all study area from 2010 to 2020, major distributed in the northern and southern.
3.3.3. Soil retention
Overall, SR also showed an upward trend during 2000 to 2020. From 2000 to 2010, the average SR increased from 26.41t/km² to 28.08 t/km², mainly concentrated in the east, whereas the average SR decreased from 28.08t/km² to 26.87 t/km² from 2010 to 2020, mainly concentrated in the southeast. The SR high value areas were mainly distributed in the east and west side of Liaoning Province, and the distribution was semblable in each period. From 2000 to 2010, the rising areas of SR accounted for 14.85% of the all study area, and the rising areas of SR accounted for 10.36% from 2010 to 2020.
3.4. ESs change in different simulation scenarios
The results of simulation scenarios in 2000-2010 showed that in only CLC effect scenario NPP, WY and SR changed by 4.08gC/m², 51.43mm/a and 1.23t/km² compared to Re1, respectively, while in only 2010 LUCC effect scenario, NPP, WY and SR changed by 50.31gC/m², -16.91mm/a and 0.44t/km², respectively. In contrast, the results of simulation scenarios in 2010-2020 showed that in only CLC effect scenario, NPP, WY and SR changed by 9.75gC/m², -25.58mm/a and -1.03t/km² compared to Re2, respectively, while in only in only 2020 LUCC effect scenario, NPP, WY, and SR changed by 60.48gC/m², -5.59mm/a and -0.18t/km², respectively.
3.5. The independent contributions of CLC and LUCC to ESs change and their dynamics
We further differentiated the independent contributions of CLC and LUCC to ESs change and their dynamics change. From 2000 to 2010, the independent contributions of CLC to WY and SR were 84.02% and 73.57%, respectively, which were higher than those in LUCC, whereas, the independent contributions of LUCC to NPP change were 92.50%. However, the independent contributions of CLC to WY change decreased by 2.65%, and to SR change increased by 16.13%, while the independent contributions of LUCC to NPP change decreased by 6.90% in 2010-2020. During 2000 to 2020, the average contributions of CLC to WY and SR change were 82.91% and 79.51%, respectively, and the average contributions of LUCC to NPP were 89.31%. Overall, CLC was the dominant factor for WY and SR change, whereas LUCC was the dominant factor for NPP change.